The Third Generation Partnership Project (3GPP) has initiated the Long Term Evolution (LTE) program to bring new technology, new network architectures, new configurations and new applications and services to wireless networks in order to provide improved spectral efficiency and faster user experiences.
A wireless transmit receive unit (WTRU) may not continually communicate with a single eNodeB (eNB) in a cell. When a WTRU moves from communicating with a first cell to a second cell, the process of switching between the two cells is known as “handover”. In an LTE network, a WTRU should be able to experience handover between a source eNB, which is an eNB in the cell that the WTRU is switching from, and a target eNB, which is an eNB in the cell that the WTRU is switching to, with little or no effect on performance of the communication link.
In some phase of the handover process in an LTE network, a WTRU must obtain information about the target eNB in order for handover to occur smoothly. One way for the WTRU to obtain information about the target eNB is for the WTRU to read a broadcast channel (BCH), which is a common downlink control channel that carries information about the eNB that is transmitting the BCH. The information may be on the primary broadcast channel (P-BCH) or the dedicated broadcast channel (D-BCH). More specifically, a master information block (MIB) that includes particular information related to the target eNB is transmitted on the P-BCH. Multiple system information blocks (SIBs) that include other information, are transmitted on the D-BCH. A WTRU may need to use a significant amount of time to read these downlink channels, due to a relatively long transmission time interval (TTI) assigned to each channel.
In a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) synchronous network, a wireless transmit receive unit (WTRU) may handover to a target cell without reading the primary broadcast channel (P-BCH) to obtain the system frame number (SFN) before it transmits a dedicated preamble in the target cell. However, the WTRU may need to know the SFN after handover for its normal operation in the target cell. Specifically, discontinuous reception (DRX) and reception of the dynamic broadcast channel (D-BCH) require the WTRU to have the knowledge of the SFN.